Not applicable.
1. The Field of the Invention
This in invention relates to apparatus for forming knotted fence mesh.
2. The Relevant Technology
Forms of fence mesh are known in which the wires forming the fence are knotted together at each or many wire intersections. In general knotted fence mesh is stronger than wire fence in which the fence wires are not knotted together at their intersections and which it is typically used for domestic or light industrial applications. Knotted fence mesh is used for applications where additional strength is required, such as for containing larger or stronger animals such as horses or deer for example.
Knotted fence mesh with a rectangular or square mesh shape for example is typically formed from a number of generally parallel line wires, which will extend generally horizontally when the fence mesh is set in position between fence posts, and lengths of stay wire which extend laterally across the line wires at regular spacings (and generally vertically when the fence mesh is set in position). In machines for forming knotted fence mesh a number of continuous line wires are fed to a bed of the machine comprising a number of similar knot boxes, and stay wire is fed into the machine bed across the line wires. Such machines typically have a step-wise operation and form a series of knots along a length of stay wire at each intersection of the stay wire and the line wires at each operational step or xe2x80x9cbeatxe2x80x9d of the machine. Typically such machines may operate at a rate of around 50 to 60 beats per minute. At each step or beat the line wires are advanced forward in parallel through the side by side knot boxes at the machine bed, stay wire is fed into the bed of the machine across the line wires at the knot boxes, at approximately 90 degrees to the line wires in case of a machine for forming rectangular fence mesh, a length of the stay wire is cut, and simultaneously at each knot box at an intersection between the line wires and the stay wire a knot securing the stay wire to the line wire is formed.
In conventional machines, these knots are formed by mechanically actuated-formers. Such machines need regular fine adjustment to ensure relatively consistent knots are formed. Further, the machines do not compensate for variations in wire diameter, tooling wear and/or build-up of wire galvanizing debris. Hence, machines having mechanically-actuated former may produce knots of varying consistency.
The invention provides an improved or at least alternative form of fence mesh forming machine. The machine of the invention is particularly suited for forming knotted fence mesh having a rectangular mesh shape and in which at each line wire-stay wire intersection a length of knot wire is wrapped or knotted around the intersection, but may be adapted for forming a knotted fence with a non-rectangular mesh shape such as a diamond mesh shape for example.
In accordance with a first aspect of the present invention, there is provided a knotted fence mesh forming machine including a machine bed with a plurality of side by side knot boxes each for forming a knot at the intersection between a line wire and a stay wire, each of the knot boxes including:
a first former arranged to move towards the line wire-stay wire intersection from one side in forming a knot at the line wire-stay wire intersection at each operation of the knot box; and
a second former arranged to move towards the line wire-stay wire intersection from a side opposite the first former at each operation of the knot box;
the machine including a hydraulic drive system arranged to move a plurality of the first former and/or the second former at each operation of the knot boxes.
The hydraulic drive system is preferably arranged to simultaneously move the first former of all of the knot boxes or the second former of all of the knot boxes at each operation of the knot boxes. More preferably, the hydraulic drive system is arranged to move the first former of all of the knot boxes simultaneously with one another and the second former of all of the knot boxes simultaneously with one another at each operation of the knot boxes.
Advantageously, one or more hydraulic cylinders are operably connected to a drive bar, which is operably connected to the plurality of the first former. In a particularly preferred embodiment, a hydraulic cylinder is operably connected to a transversely moveable rack bar having a plurality of camming surfaces defined therein, and a plurality of cam followers extend from the drive bar, each cam follower engaging with a respective one of the camming surfaces, the camming surfaces being arranged such that transverse movement of the rack bar results in orthogonal movement of the drive bar, thereby moving the first former.
Alternatively, the machine includes a plurality of hydraulic cylinders, with a ram of each hydraulic cylinder being operably connected to a respective first former.
Similarly, one or more hydraulic cylinders may be operably connected to a drive bar, which is operably connected to the plurality of the second former. Again, in a particularly preferred embodiment, a hydraulic cylinder is operably connected to a transversely moveable rack bar having a plurality of camming surfaces defined therein, and a plurality of cam followers extend from the drive bar, each cam follower engaging with a respective one of the camming surfaces, the camming surfaces being arranged such that transverse movement of the rack bar results in orthogonal movement of the drive bar, thereby moving the second former.
Alternatively, the machine includes a plurality of hydraulic cylinders, with a ram of each hydraulic cylinder being operably connected to a respective second former.
Each knot box preferably includes a first support arranged to support the line wire-stay wire intersection from the side opposite the first former during movement of the first former.
One or more hydraulic cylinders may be operably connected to a drive bar, which is operably connected to the plurality of first supports. In a particularly preferred embodiment, a hydraulic cylinder is operably connected to a transversely moveable rack bar having a plurality of camming surfaces defined therein, and a plurality of cam followers extend from the drive bar, each cam follower engaging with a respective one of the camming surfaces, the camming surfaces being arranged such that transverse movement of the rack bar results in orthogonal movement of the drive bar, thereby moving the first supports.
Alternatively, the machine may include a plurality of hydraulic cylinders, with a ram of each hydraulic cylinder being operably connected to a respective first support. In a preferred embodiment, each hydraulic cylinder has two rams, with one ram operably connected to a respective first support and the other ram operably connected to a respective second former.
Each knot box preferably includes a second support arranged to support the line wire-stay wire intersection from the side opposite the second former during movement of the second former.
One or more hydraulic cylinders may be operably connected to a drive bar, which is operably connected to the plurality of second supports. In a particularly preferred embodiment, a hydraulic cylinder is operably connected to a transversely moveable rack bar having a plurality of camming surfaces defined therein, and a plurality of cam followers extend from the drive bar, each cam follower engaging with a respective one of the camming surfaces, the camming surfaces being arranged such that transverse movement of the rack bar results in orthogonal movement of the drive bar, thereby moving the second supports.
Alternatively, the machine may include a plurality of hydraulic cylinders, with a ram of each hydraulic cylinder being operably connected to a respective second support. In a preferred embodiment, each hydraulic cylinder has two rams, one ram being operably connected to a respective second support, the other ram being operably connected to a respective first former.
In accordance with a second aspect of the present invention, there is provided a knotted fence mesh forming machine including a machine bed with a plurality of side by side knot boxes each for forming a knot at the intersection between a line wire and a stay wire, each of the knot boxes including:
a former arranged to move towards the line wire-stay wire intersection from one side and form a knot at the intersection at each operation of the knot box;
the machine including a drive system arranged to move a plurality of the former at each operation of the knot boxes;
wherein at least some of the former are hydraulically driven and/or hydraulically damped.
A hydraulic drive system may be provided to simultaneously move a plurality of the former at each operation of the knot boxes.
The hydraulic drive system preferably includes one or more hydraulic cylinders operably connected to a drive bar, which is operably connected to the plurality of the former. In a particularly preferred embodiment, a hydraulic cylinder is operably connected to a transversely moveable rack bar having a plurality of camming surfaces defined therein, and a plurality of cam followers extend from the drive bar, each cam follower engaging with a respective one of the camming surfaces, the camming surfaces being arranged such that transverse movement of the rack bar results in orthogonal movement of the drive bar, thereby moving the former.
Alternatively, the drive system includes a plurality of hydraulic cylinders, with a ram of each hydraulic cylinder being operably connected to a respective former.
Advantageously, each former is hydraulically damped. In a preferred embodiment, a damping hydraulic cylinder is operably connected to each former. Each damping hydraulic cylinder may be located in a respective former holder.
In a preferred embodiment, each damping hydraulic cylinder is pressurized to a constant pressure. The drive system may be arranged to over-stroke when moving a plurality of the former at each operation of the knot boxes, and the damping hydraulic cylinders may be arranged to compress slightly, thereby providing even pressure to each former at each operation of the knot boxes.
Each former is preferably a final former.
Preferably each knot box includes a first former arranged to move towards the line wire-stay wire intersection from a side opposite the final former at each operation of the knot box, prior to or concurrently with the movement of the final former.
A hydraulic drive system may be provided to simultaneously move a plurality of the first former at each operation of the knot boxes.
The hydraulic drive system preferably includes one or more hydraulic cylinders operably connected to a drive bar, which is operably connected to the plurality of the first former. In a particularly preferred embodiment, a hydraulic cylinder is operably connected to a transversely moveable rack bar having a plurality of camming surfaces defined therein, and a plurality of cam followers extend from the drive bar, each cam follower engaging with a respective one of the camming surfaces, the camming surfaces being arranged such that transverse movement of the rack bar results in orthogonal movement of the drive bar, thereby moving the first former.
Alternatively, the drive system includes a plurality of hydraulic cylinders, with a ram of each hydraulic cylinder being operably connected to a respective first former.